<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            /* 边框颜色 */
            background: #4CAF50;

            /* 字体颜色 */
            color: white;
            
            width: 80%;
            height: 50px;
            /* 填充 */
            padding: 15px;
            
            border: 1px solid black;
            
            /* overflow: 属性:hidden隐藏 visible可看到 scroll上下滚动; */
            overflow: scroll;
            
        }
    </style>
</head>
<body>
    <div>
        <p>这个边框会越界aaaaaaaaaaaaaaaaaaaaaasssssssssssssssssssssssssss</p>
    </div>
</body>
</html>